Anti-tack bladder

ABSTRACT

A bladder with an anti-tack rubber having suitable curing properties to turn up plies in manufacturing pneumatic tires is provided. In a preferred embodiment, the anti-tack rubber comprises 50 to 45 parts natural rubber cured with 50 to 60 parts chlorosulfonated polyethylene, 0.9 to 1.1 benzothaizyl disulfide and 0.9 to 1.1 phenylenediamine. A method of making the anti-tack rubber comprises mixing a first rubber and an anti-tack composition and blending curing agents to form a workable anti-tack rubber with suitable curing properties. An improved and simplified method to form a bladder with suitable anti-tack and curing properties, and a method for using a bladder to turn plies in manufacturing pneumatic tires, wherein the bladder is made from an anti-tack rubber is also disclosed.

FIELD OF THE INVENTION

The invention relates primarily to an anti-tack bladder made with ananti-tack rubber for use with an apparatus for manufacturing pneumaticvehicle tires, more specifically with inflatable rubber bladdersconventionally used to turn ply ends over a tire bead ring and againsttire plies on a tire building mandrel. Methods for making and using ananti-tack bladder and an anti-tack rubber are provided.

BACKGROUND OF THE INVENTION

Tire building or assembly machines (TAMS) conventionally use rollinginflatable rubber bladders to turn up plies of rubber material that havebeen wrapped around a tire building mandrel, a type of rotatingcollapsible drum. The bladder is known as a turn-up bladder and servesto turn up the plies over a bead formed from wire cables embedded in atough hard rubber. The rubber ply material is tacky by nature to allowthe turned up plies to stick together to form the side wall of the tire.The turn-up bladders are conventionally made of various elastomericmaterials such as vulcanized rubber, natural (cis-1,4-polyisoprene)and/or synthetic rubber (i.e., styrene-butadiene) or mixtures thereof.The turn-up bladders will often stick to the uncured or partially curedplies when they are rolled over the beads to form part of the tire asthey are inflated, typically, with compressed air. This adhesion slowsthe turn-up process by impeding the retraction of the deflated turn-upbladder and also results in decreased turn-up bladder life due toerosion caused by such adhesion to the plies.

U.S. Pat. No. 4,381,331 (Johnson) discloses a solution to the abovetacking problem by having a ply turn-up bladder with at least a portionof its outer surface comprising a fabric layer of spaced cordscalendered, (i.e., rolling a rubber compound into the fabric onmulti-roll calender machines) with a coating of unvulcanized, uncuredrubbery polymer partially embedded in the rubbery polymer surface. Thespaces between such cords are free of the polymer so the cords canproject above this polymer surface. This arrangement allows thepolymer-free cords to contact the tacky plies, thereby reducing itsadhesion to the turn-up bladder. The disadvantage of this solution arethe complex finishing steps associated with preparing this outer fabriclayer, such as a separate heating step to additionally cure a separatelyapplied coating, and abrading the surface of the cords to remove some ofthe cured polymer to expose them. Consequently the Johnson bladder iscostly to make.

U.S. Pat. No. 5,213,823 (Hunt) discloses a turn-up bladder made with ahigh release outside layer bonded to a core sulfur-cured rubber base,wherein the outside layer is cured in a conventional manner. The highrelease layer is formed from a mixture or blend of polyvinyl chlorideand acrylonitrile-butadiene rubber, with a plasticizer and conventionalrubber compounding ingredients. One example of a polyvinyl chloride andacrylonitrile-butadiene rubber blend that has been used is “Paracil OZO”50, manufactured by Uniroyal, Inc. of Middlebury, Conn., USA, furtherdescribed in U.S. Pat. No. 3,993,607 (Florence).

Yet another solution to the ply end tacking problem is to apply acoating to the turn-up bladder itself, such as a spray coat disclosed inU.S. Pat. No. 4,359,350 (Comper). The described coating is an aqueouslubricant containing polydimethylsiloxane, a silane, a surfactant, andoptionally, a metal salt of an organic acid.

U.S. Pat. No. 5,104,477 (Williams) discloses a method to apply a surfacecoating of controlled release characteristics to a turn-up bladdercomprising the steps of applying a releasing composition, removing avehicle to form an adhering film, and curing the film to form theexposed release coating. The composition of the release coating isdisclosed as comprising a chlorosulfonated polymer, a reinforcingfiller, a green tack agent, and inert volatile solvent/diluent viscosityreducing vehicles. HYPALON, chlorosulfonated polyethylene, manufacturedby E.I. duPont de Nemours and Co., of Wilmington, Del. is disclosed as asuitable chlorosulfonated polymer. Typical reinforcing fillers arecarbon black, silica, fumed silica, silica dioxide and various claysknown in the art, which can be used to reinforce the elastomercompositions. The green (referring to uncured, unvulcanized rubber orelastomer, not color) tack agent is typically a resin such asalkaphenol/formaldyhyde, chlorinated paraffin resins, poly(beta) terpeneresins, and other resins disclosed in U.S. Pat. No. 5,104,477. Chemicalcuring systems are also added to the releasing composition and includesulphur-based systems containing conventional amounts ofnitrogen-containing accelerator and activators known in the art.Additionally, metallic oxides such as litharge, magnesia, and sulphurbearing organic compounds and epoxy resins can be used. Typical inert,viscosity-reducing solvent/diluent vehicles are composed of organicliquids having a normal boiling point between 20-200 deg. C. Thesesolvent vehicles function to solublize or disperse the releasingcomposition to enable its application as a thin film on the turn-upbladder.

One problem to be solved is that of designing an anti-tack bladderavoiding the need to coat an anti-tack material onto the surface of analready formed bladder, which would comprise an additional and morecomplex preparation step in manufacturing the bladder. In particular,the problem to be solved is that of departing from the use of a thinfilm composite to cover the bladder surface: as a matter of fact, thefilm(s) must be uniform and able to withstand fractures, while at thesame time providing sufficient flexibility, with good adhesion to thebladder and with the ability to properly control adhesion to the ply.The production of such a film is problematic and furthermore, the curingof a film of this kind on a bladder surface is a very complex step.

Yet another problem to be solved is that of avoiding the use of theadditional hazardous materials and solvents which are involved informing a vehicle to apply the coating; such materials can in fact, poseincreased environmental processing costs, as well as storage andhandling safety risks.

What is desired, therefore, is an inflatable bladder with reducedadhesion to a ply, improved flexibility, better fracture resistance, allwithout the need to form such a material with an involved multi-stepprocess requiring abrading, applying a separate coating material (suchas a liquid, paste, or gel-like material), removal of a solvent vehicle,or depositing a final uniform coating to form the bladder's anti-tackproperties.

What is also desired, therefore, is an inflatable bladder with suitablecuring and anti-tack properties for use with an apparatus formanufacturing pneumatic tires. Suitable anti-tack properties in tiremanufacturing allow for quick, unimpeded release of green, cured andpartially cured rubber from elastomeric structures such as flexiblebladders, bags, diaphragms, sleeves, and the like. Suitable curingproperties of rubber used in a bladder include high durability, good cutresistance and rebound suitable for repeated inflation and deflationcycles characteristic in pneumatic tire manufacturing. The inflatablebladder should exhibit suitable curing and anti-tack properties withoutany visible cracking, peeling or erosion of the anti-tack bladder bodyunder operating conditions and parameters associated with pneumatic tiremanufacturing, such as capacity, bladder life, operating pressure and/orcycle time. When a rubber material is provided with such anti-tack andcuring properties the bladder can be directly manufactured from, thisallows a bladder to be formed without the need of additional processingsteps to impart such anti-tack properties thereby simplifying productionwhile reducing the potential for tire manufacturing down time.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide an inflatablebladder with suitable anti-tack properties for use in pneumatic tiremanufacturing which is relatively simple in construction, and comprisesan anti-tack rubber the body of the bladder can be manufactured from.

Another object of the invention is to provide an anti-tack rubber withsuitable anti-tack and curing properties which allow for unimpededrelease of green, cured and partially cured rubber from elastomericstructures such as flexible bladders, bags, diaphragms, sleeves, andother applications which benefit from a curable rubber with anti-tackproperties.

A further object of the invention is to provide an anti-tack rubber withsuitable curing properties which diminishes the risk that the anti-tackcomposition will wear off due to erosion, cracking or fracture when usedwith an inflatable bladder under operating conditions associated withpneumatic tire manufacture.

Another object of the invention is to provide an anti-tack rubber havingsufficient tack to adhere to the ply-ends used in conventional tiremanufacture without adhering to a turn-up bladder such that the turn-upbladder is eroded by contact with the ply-ends.

Yet another object of the invention is to provide a method to make ananti-tack rubber capable of achieving the above objects which mixes atleast a first rubber and an anti-tack material in a single step.

Still another object of the invention is to provide a method to make aninflatable bladder capable of achieving the above objects that comprisesforming an anti-tack rubber into a first ply and adhering the first plyto an elastomeric material as part of a complete bladder manufacturingprocess.

Another object of the invention is to provide a method to make aninflatable bladder capable of achieving the above objects that issimpler, more efficient, and environmentally benign without the need fora multi-step curing process requiring direct coating, depositing andremoving a vehicle on the bladder.

Yet another object of the invention is to provide a method to use aninflatable bladder capable of achieving the above objects that comprisesinflating, contacting and deflating a bladder with an anti-tack rubberthat releases from contact with cured, partially cured, or uncured tirerubber with inherently less risk of eroding, cracking or peeling. Otherobjects of the invention will be obvious and may in part appearhereinafter.

These and other objects are achieved by the present invention whichprovides: an inflatable bladder comprising a body made of an anti-tackrubber, a method to make an anti-tack rubber, a method to make aninflatable bladder with suitable anti-tack and curing properties formanufacturing pneumatic tires, and a method to use an inflatable bladderwith an anti-tack rubber in manufacturing pneumatic tires and turningtire plies over a bead ring.

The inflatable bladder according to the invention comprises: anelastomeric material having an outer surface, wherein at least a portionof said outer surface comprises an anti-tack rubber, said anti-tackrubber containing a blend of a first rubber and an anti-tackcomposition, wherein said anti-tack rubber has suitable curing andanti-tack properties for use with an apparatus for manufacturingpneumatic tires.

A method to make an anti-tack rubber according to the inventioncomprises: combining a first rubber and a chlorosulfonated polyethylene;adding fillers, reinforcing agents, processing aids, and plasticizers;blending into the mix cross-linking agents, metal oxides, cureaccelerators, and cure activators to form said anti-tack rubber withsuitable curing properties for use with an inflatable bladder inmanufacturing pneumatic tires; and forming the anti-tack rubber into aseparate workable ply. More preferred blends of the anti-tack rubbercontain 50 to 45 parts of a natural rubber cross-linked with 55 to 60parts of a chlorinated polyethylene, 0.9 to 1.1 parts ofphenylenediamine, and 0.9 to 1.1 parts of benzothiazyl disulfide.

The invention in one of its aspects also provides a method to make aninflatable bladder with suitable curing and anti-tack properties formanufacturing pneumatic tires. Such a method comprises the steps of:mixing at least a first rubber and a anti-tack material to form ananti-tack rubber, forming the anti-tack rubber into a ply, and adheringthe anti-tack rubber to an elastomeric material of the inflatablebladder. In another embodiment, the inflatable bladder can be madeentirely from a ply of the anti-tack rubber.

In another aspect, the invention provides a method to use an inflatablebladder in tire manufacturing comprising the steps of: inflating thebladder having an anti-tack rubber; contacting a rubber tire materialwith the bladder, and deflating the bladder with suitable cure andanti-tack properties so as to release from contact with the rubber tirematerial upon deflation.

In another embodiment, the invention provides a method to use theinflatable bladder specifically for turning tire plies over a bead ringcomprising cycles of; wrapping tire plies on a tire building drum;positioning bead rings on the tire building drum; inflating the bladderto turn the tire plies over the bead rings; and deflating the bladdercontaining an anti-tack rubber with suitable cure and anti-tackproperties so as to release from the tire plies upon repeated deflationcycles.

The invention and its particular features will become more apparent fromthe following detailed description considered with reference to theaccompanying drawings and example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-section showing a tire building machineusing a rolling anti-tack bladder to turn tire plies up and around abead ring where the bladder is shown in a partially deflated statereleased from the tire plies after the plies have been turned around abead ring. The bladder is shown in an alternative inflated state.

FIG. 2 is a schematic cross-section showing an alternative embodiment ofa tire building machine using two rolling bladders to turn tire plies upand around a bead ring showing a first anti-tack bladder in a partiallydeflated state released from the tire plies, and a second bladder in adeflated state. The second bladder functions to aide in turning up thefirst bladder. The bladders are shown in an alternative inflated state.

FIG. 3 is a schematic cross-section showing an alternative embodiment ofthe inflatable anti-tack bladder of this invention where the anti-tackrubber forms a separate ply adhered to the body of the bladder.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts an anti-tack bladder 50 comprising an anti-tack rubber 30and an elastomeric bladder material 40, shown in a partially deflatedstate, mounted on a tire building machine having a drum or mandrel 13.One edge of the bladder 50 is clamped between mounting rings 14 and 15,the other edge of bladder 50 is clamped between mounting rings 15 and16. The body of a tire ply, ply body 12 is shown wrapped around themandrel 13. A bead ring 20 is then positioned on the mandrel 13. Theanti-tack bladder 50 is shown in a partially deflated state and releasedfrom tire ply 10 after bladder 50 has folded tire ply 10 around tirebead ring 20 and against ply body 12. When the anti-tack bladder 50 isinflated, as shown by the position of the broken lines, it folds a tireply 10 over and around the tire bead ring 20 and against the ply body12. A cycle for turning the tire ply 10 up and around bead ring 20 iscomplete upon deflation and release of the anti-tack bladder 50 from thetire ply 10. A new cycle starts upon inflation of the anti-tack bladder50 to turn another ply up and around bead ring 20.

FIG. 2 depicts another embodiment of the present invention using ananti-tack bladder 50 with another bladder 41 on a tire building machine.Bladder 50 performs the same function as bladder 50 in FIG. 1, howeverbladder 41 is not an anti-tack bladder and serves to push anti-tackbladder 50, which in turn contacts tire ply 10, up and over tire beadring 20. FIG. 2 shows anti-tack bladder 50 in a partially deflatedstate, released from tire ply 10 after anti-tack bladder 50 has foldedtire ply 10 around tire bead ring 20 and against a ply body 12. FIG. 2also shows bladder 41 completely deflated and alternatively, as shown bythe position of the broken lines, in an inflated state pushing upanti-tack bladder 50.

FIG. 3 shows a particular embodiment of an anti-tack bladder 50 of theinvention comprising an anti-tack rubber 30 adhered to an elastomericbladder material 40 to form the body of an inflatable anti-tack bladder.

One of the advantages of the anti-tack bladder of the present inventionis that, because an anti-tack composition is blended with a firstrubber, forming an anti-tack rubber 30, there is no need to apply acoating material (such as a liquid, paste, or gel-like material) to anelastomeric compound that forms the bladder body in order to achievesuitable anti-tack and cure. properties for manufacturing pneumatictires. The anti-tack composition is blended with the first rubber toform a separate and new anti-tack rubber and therefore there is no needfor a multi-step curing process requiring direct coating of the bladderbody or depositing the anti-tack composition with a solvent or viscosityreducing vehicle to form an anti-tack coating or layer. As such, theanti-tack rubber that results from the present invention can form aseparate workable rubber ply. This then eliminates additional processingsteps from the prior art and results in a simpler, more efficient methodto form an anti-tack bladder without the need of handling and usingadditional solvents, or coatings. The overall productivity of thebladder manufacturing process can therefore be increased, as well asproviding environmental benefits from eliminating additional solventuse.

Another advantage of the anti-tack bladder of the present invention isthe reduced risk the anti-tack composition will crack, peel or erode onthe bladder body from contact with the sticky tire ply 10 duringrepeated inflation and deflation turn-up cycles, as the anti-tackbladder of the present invention is not the result of merely ananti-tack coating or layer of an anti-tack composition, but is acomplete rubber formulation with anti-tack and curing propertiessuitable for use in pneumatic tire manufacturing. As a result, theanti-tack composition is cross-linked with a first rubber to form asingle anti-tack rubber 30. The anti-tack rubber 30 resulting from thisformulation exhibits suitable curing and anti-tack properties for use asa bladder body material in pneumatic tire manufacturing.

What is meant by “suitable” curing properties is as measured by usingASTM D 2084 Method for Rubber Property Vulcanization Using OscillatingDisk Cure Meter, which is hereby incorporated by reference, and displaysmodulus, tensile strength and elongation properties characteristic ofthe cure curve data disclosed in Table 2 of this specification. Suchphysical properties of cured rubber compounds or vulcanizates are morefully described in the Vanderbilt Rubber Handbook 13 ed., edited byRobert F. Ohm (Norwalk, Conn., R. T. Vanderbilt Co., Inc., 1990), pages518-541, which is hereby incorporated by reference. Curing orvulcanization of rubber changes its physical properties and increasesviscosity, hardness, modulus, tensile strength, abrasion resistance andrebound. The turn-up bladder must be composed of a rubber that hassuitable physical properties associated with high durability, good cutresistance and rebound because it is characteristically subject torepeated inflation and deflation cycles in the pneumatic tiremanufacturing process. One of the advantages of the present invention isthat an anti-tack composition is cured with a rubber to form ananti-tack rubber with such suitable curing properties for use inmanufacturing pneumatic tires, more specifically, for repeated inflationand deflation cycles as a bladder.

What is meant by “suitable anti-tack properties” is that the bladderretains its flexibility and does not exhibit visible erosion or stickingto green, cured and partially cured rubber from elastomeric structuresused and observed in actual tire manufacturing. Therefore, because theanti-tack properties of the present invention are achieved from a singleanti-tack rubber formulation with suitable curing properties, there isno risk the anti-tack properties will be reduced due to fracturing,cracking, peeling, or eroding of an applied anti-tack composition aswith the prior art solutions.

Another advantage of the present invention where the anti-tackproperties of the bladder result from a single anti-tack rubberformulation with suitable curing properties, is that there is also norisk that the flexibility, durability, and workability of the rubberbladder will be compromised. A disadvantage that the present inventionovercomes is the risk that an anti-tack composition does not exhibitequivalent curing properties to the elastomeric material forming thebladder body when it is adhered as a separate layer or coating to arubber bladder. This risk is eliminated with the anti-tack rubber 30 ofthe present invention because the anti-tack properties of the bladderresult from a single anti-tack rubber formulation with suitable curingproperties as described.

A further advantage of an embodiment of the anti-tack bladder of thepresent invention is that the bladder body can be constructed of theanti-tack rubber 30. This allows the bladder to be manufactured withoutthe need to formulate a separate anti-tack material and adhere it to thebladder body, thereby saving a manufacturing step which allows increasedbladder manufacturing productivity along with a bladder that is freefrom any potential defects from adhering a separate anti-tack materialto a rubber bladder body.

Yet another advantage of the anti-tack bladder of the present inventionrelates to the properties associated with the formulation of ananti-tack rubber. Because the anti-tack properties of the bladder resultfrom formulating an anti-tack rubber with suitable curing and anti-tackproperties for use in manufacturing pneumatic tires as indicated by ASTMD 2084, hereby incorporated by reference, and not merely from a layer orcoating of an anti-tack composition, the anti-tack bladder can befabricated with minimal change to a plant's existing bladdermanufacturing process.

In an alternative embodiment, the anti-tack bladder can be manufacturedby adhering a ply ranging from about 0.030 to about 0.040 inches inthickness of the anti-tack rubber in accordance with the presentinvention to a bladder body 40 by means such as applying to the bladderbody 40 a tackifying agent, cement, calendering, or by application as alaminate ply, such as disclosed in U.S. Pat. Nos. 5,213,823 and5,250,142, hereby incorporated by reference, or by any otherconventional means as part of a plant's existing manufacturing processto form the inflatable bladder. Typically, a conventional bladder can beformed of several rubber plies, with or without reinforcing fabric ormaterial. Therefore, the anti-tack bladder of the present invention canretain the same conventional bladder fabrication process with simplyadding another rubber ply of the anti-tack rubber 30 to adhere to anyother ply or plies already comprising an elastomeric bladder material40. Therefore, creation of the anti-tack bladder of the presentinvention could be performed without any new or different adhering stepsif a multi-ply bladder had previously been used.

In the practice of this invention, an anti-tack bladder is formed bycreating an anti-tack rubber wherein at least a portion of the bladder,e.g. the portion contacting a green tire ply, can be constructed from,as shown in FIGS. 1 and 2. This being opposed to merely coating thebladder with an anti-tack composition.

The anti-tack rubber contains a blend of a first rubber, and ananti-tack composition to provide an anti-tack rubber with suitableanti-tack and curing properties for use in pneumatic tire manufacturing.The first rubber may be a natural or synthetic rubber, or a mixture ofthe two. By the term natural rubber, it is meant rubber obtained fromnatural sources or its chemical equivalent, such ascis-1,4-polyisoprene. Examples of synthetic rubbers include rubber likepolymers produced by polymerizing aliphatic, conjugated diolefins suchas butadiene, isoprene pentadienes, etc. The rubbers contain unsaturatedcarbon chains, and such rubbers are known in the art as shown byANSI/ASTM Standard D1418-85A, hereby incorporated by reference, wherethese rubbers are referred to as R rubbers and disclosed in U.S. Pat.No. 5,552,483, which is hereby incorporated by reference. Natural rubberis employed in preferred embodiments. Mixtures of rubbers may also beemployed. Some of the R rubbers will have a solubility parameter ofabout 8.1 or less, as well known in the art.

An anti-tack composition may be a halogenated and sulfonated polymerthat shows suitable anti-tacking properties as well as good strength andflexibility for use as a bladder component in pneumatic tiremanufacturing. Chlorosulfonated polyethylene is the preferred embodimentfor an anti-tack composition.

In a preferred embodiment, an anti-tack rubber is formed by blending anatural rubber, such as cis-1,4-polyisoprene, or a synthetic rubber suchas stryrene-butadiene, or mixtures thereof, with an anti-tackcomposition, preferably a chlorosulfonated polyethylene that whencross-linked with the rubber, results in a formulation exhibitingsuitable curing properties for use in manufacturing pneumatic tires.Anti-tack rubbers and rubber blends of this invention are processed witheffective amounts of processing aids, accelerators, cross-linking andcuring materials, anti-degradants, fillers and the like, to provide ananti-tack rubber with suitable curing properties for use with aninflatable bladder in manufacturing pneumatic tires.

Processing aids can include, but are not limited to, processing oils,waxes, plasticizers, preferably n-phenyl-p phenylenediamine, extenders,chemical conditioners, homogenizing agents and peptizers, such asmercaptans, petroleum and vulcanized vegetable oils, resins, rosins, andthe like as known in the art. See Vanderbilt Rubber Handbook, 13 ed.,published by the R. T. Vanderbilt Co., of Norwalk, Conn., (1990), pages275-289, which is hereby incorporated by reference.

Accelerators include thiazole types such as MBTS (Benzoythiazyldisulfide) and MBT (Mercaptobenzothiazole), TMTD (Tetramethylthiuramdisulfide), and TETD (Tetraethylthiuram disulfide). Cross-linking andcuring agents include sulfur, zinc oxide, and fatty acids.Chlorosulfonated polyethylene can be cross-linked by a variety of curingsystems. Curing systems based on zinc-oxide-magnesia as acid receptorsare most useful. Antidegradants include antioxidants and antiozonantsknown in the art. Fillers include carbon black, calcium carbonates andmineral fillers such as silica and clay known to increase hardness,strength and resistance to tear or abrasion.

Some of the materials needed to prepare and practice the invention areknown in the art, and in other cases can be prepared by those skilled inthe art without undue experimentation. For example, chlorosulfonatedpolyethylene, known as HYPALON, is commercially available from E. I.duPont de Nemours and Co., of Wilmington, Del.. Such materials aredescribed in the literature, see Vanderbilt Rubber Handbook, 13 ed.,published by the R. T. Vanderbilt Co., of Norwalk, Conn., (1990), pages752-758, which is hereby incorporated by reference.

Preferred forms of the anti-tack rubber are further characterized asconforming to the following analysis based on parts by weight.

TABLE 1 PREFERRED ACCEPTABLE RANGE RANGE COMPONENT (parts) (parts)Rubber material 40-45 40-45 Anti-tack material 55-60 55-60Reinforcing/filler material 34.5-40.5 30.0-45.0 Processing oil 2.5-3.52.0-4.0 Activator 4.5-5.5 3.0-5.5 Plasticizer/pH control 1.8-2.2 1.0-3.0Wax 2.5-3.5 2.0-3.5 Filler 4.5-5.5 3.0-5.5 Scorch inhibitor 12-14 12-14Cross-linking/vulcanizing agent 0.9-1.1 0.95-1.5  Accelerator 0.9-1.10.6-1.5

The anti-tack rubber of the invention is prepared by mixing thematerials in a single step or in stages using various types of mills,blenders and mixers known in the art. For example, the rubber blend of afirst rubber and an anti-tack composition can be processed with a fillerwax, antidegradants, processing oil with accelerators, curing andcross-linking agents, and the remaining antidegradants added in a singlestage. The single stage is the preferred embodiment, however, additionalstages may involve incremental additions of the other materialsdescribed.

Example formulations of an anti-rubber used in the anti-tack bladder areset forth hereinafter.

The following example illustrates preparation of the anti-tack rubberand an anti-tack bladder of the invention. The example is presented tofurther illustrate and explain the present invention and should not betaken as limiting in any regard. Unless otherwise indicated in theexample and elsewhere in the specification and claims, all parts andpercentages are by weight. Percentages are based on 100 parts by weightof rubber, i.e., the natural rubber and the chlorosulfonantedpolyethylene. Temperatures are degrees centigrade.

EXAMPLE 1

This example describes one typical composition of the anti-tack rubberof the invention. The anti-tack rubber is formed by mixing a naturalrubber, cis-1,4-polyisoprene, and a chlorosulfonated polyethylene toform a mix, adding fillers, reinforcing agents, processing aids, andplasticizers. Cross-linking agents, metal oxides, cure accelerators, andcure activators are blended into the mix in a Banbury mixer untilhomogeneous. A compound having the following composition by parts wasprepared:

Natural rubber 43 Chlorosulfonated polyethylene 57 Carbon black (N660) 5(ASTM D1765) Calcium carbonate 32.2 Processing oil 3 Zinc oxide 5Stearic acid 1 n-phenyl-p-phenylenediamine 1 Wax 3 Titanium dioxide 5Magnesium oxide 13.3 Sulfur 0.96 Benzothiazyl disulfide 1

Cure properties are obtained using an oscillating disk rheometer,operated at 151 deg. C. and at a frequency of 100 cpm. A description ofoscillating disc rheometers is found in the Vanderbilt Rubber Handbook13 ed., edited by Robert F. Ohm (Norwalk, Conn., R. T. Vanderbilt Co.,Inc., 1990), pages 554-558, which is hereby incorporated by reference.The cure meter procedure and standardized time v. torque values arespecified in ASTM D 2084 and also described in U.S. Pat. No. 4,790,365(Sandstrom), which are hereby incorporated by reference.

The anti-tack rubber composition prepared according to this exampleexhibited the following cure data summarized in Table 2.

TABLE 2 Oscillating disk Rheometer @ 100 cpm, 151 deg. C. ASTM D 2084M_(I)  9.3 M_(L)  6.0 M_(H2) 23.6 t₈  8.1 t₅₀ 18.5 t₉₀ 46.4 M_(I) =torque @ 1 min. M_(L) = minimum torque M_(H2) = maximum torque @ 2 min.t_(x) = time to x% of maximum torque. All torque units are dn.m. Time isminutes.

Once the anti-tack rubber is formed into a ply, it is then cured to formthe body of the anti-tack bladder. An uncured ply of the anti-tackrubber prepared according to Example 1 is adhered to the body of anelastomeric material known in the art to be used for making inflatablebladders for tire manufacturing. The anti-tack bladder is then made bypositioning a reinforcement fabric of natural rubber calander stock on adrum of a bladder building machine. A second sheet of natural rubbercalander stock is then positioned on the reinforcement fabric. Anothersheet of natural rubber calander stock is then positioned on the sheetof natural rubber calander stock. The anti-tack rubber is thenpositioned on the natural rubber calander stock. The drum unit is thenremoved from the bladder building machine and cured. Curing a ply of theanti-tack rubber to form the anti-tack bladder is done with an autoclaveprocess as known in the art, where the autoclave is operated for 50minutes at 144 deg. C. at 80 psig.

In order to better evaluate the effectiveness of the anti-tackproperties of the invention, a turn-up bladder containing an anti-tackrubber according to the formulation set forth in Example 1 was usedunder actual operating conditions in a tire manufacturing facility underthe operating conditions summarized in Table 3.

TABLE 3 Turn-up bladder evaluated: 14 inch size. An A70 tire buildingmachine (Pirelli design) was used. Operating Pressure Lower bladder, 22psi Upper bladder, 8 psi Cycle time 2 min./tire

After a period of approximately 20,000 cycles, which is the standardlife of the prior art bladders, the practical results have been novisible cracking, peeling or erosion of the anti-tack bladder body ofthe present invention from contact with the sticky tire ply 10 duringrepeated inflation and deflation turn-up cycles. Furthermore during thatperiod, the bladder of the invention did not stick to the uncuredcarcass plies of the worked tires.

These and other advantages which will be apparent to one skilled in theart, are clearly beneficial and enable the process of manufacturingtires, and anti-tack bladders used therein, to be carried out withreduced complexity of process without a sacrifice of quality and curingproperties of an anti-tack bladder. It is understood that, while thepresent invention is disclosed in terms of its use in manufacturingpneumatic tires, the present invention is likewise useful in similaroperations where an anti-tack rubber can be applied.

The above description is for the purpose of teaching the person ofordinary skill in the art how to practice the present invention, and isnot intended to detail all those obvious modifications and variations ofit, which will become apparent to the skilled worker upon reading thedescription. It is intended, however, that all such obviousmodifications and variations be included within the scope of the presentinvention, which is defined by the following claims.

What is claimed is:
 1. An inflatable bladder comprising; an elastomericmaterial having an outer surface, wherein at least a portion of saidouter surface comprises an anti-tack rubber, said anti-tack rubbercontaining a blend of natural rubber and chlorosulfonated polyethylene,wherein said anti-tack rubber has suitable curing and anti-tackproperties for use with an apparatus for manufacturing pneumatic tires.2. An inflatable bladder according to claim 1, wherein said anti-tackrubber forms a separate first ply, said first ply adhered to said outersurface of said elastomeric material, wherein said first ply hassuitable curing and anti-tack properties for use with said elastomericmaterial in manufacturing pneumatic tires.